1. Field of the Invention
This invention relates to an apparatus for changing the relative phase angles of output shafts of an electric, multiple motor drive. More particularly, the invention relates to such arrangements in which the individual shafts are coupled to synchronous motors which can be connected to an operating static frequency changer having an output voltage which depends, as to frequency and phase, on the control frequency of a frequency generator.
2. Description of the Prior Art
Various production machines require the use of different speeds to accommodate the flow of articles or material. For instance, in the manufacture of bottles in a hollow-glass machine, different speeds are required at the different operating levels, e.g., the drop distributor, the control drum, etc.
However, the drives of the different speed levels must be in synchronism with each other. In addition, it must be possible to correct the mechanical phase of individual drives relative to one another; that is, it must be possible to reposition the output shafts by advancing or retarding the relative angle, so that, thereby, the flow of goods or material can be optimized.
This problem can be solved by using a decentralized drive, i.e., by using a separate synchronous motor for each operating level, and by supplying the motors from a central operating frequency changer; the motors will then be in synchronism. Heretofore in order to match the phase angle of the different output shafts to each other appropriately, a planetary drive (differential) has been used, with each drive being followed by such a transmission. In this way, the appropriate phase angle could be adjusted manually by means of a hand wheel.
It is an object of the present invention to replace the mechanical arrangement by an electrical arrangement, thereby improving operating convenience and reducing costs.